王存等《Journal of integrative plant biology》2021年

论文题目：GTPase ROP6 negatively modulates phosphate deficiency through inhibition of PHT1;1 and PHT1;4 in Arabidopsis thaliana

论文作者：Huiling Gao, Tian Wang, Yanting Zhang, Lili Li, Chuanqing Wang, Shiyuan Guo, Tianqi Zhang and Cun Wang

ROPs作为植物体内重要的分子开关，，参与调控众多的信号转导过程。但其是否参与植物低磷信号转导途径却鲜有报道，其分子机制更是知之甚少。该研究发现拟南芥rop6突变体对砷胁迫显著敏感，ROP6OE对砷胁迫明显耐受，回复突变体能够恢复到野生型的表型。进一步研究表明，rop6突变体对低磷胁迫明显耐受，主根更长，花青素含量降低，磷吸收能力增强，磷含量显著升高。低磷胁迫处理条件下，ROP6蛋白活性降低并被26S蛋白酶体降解。通过蛋白-蛋白互作证明，ROP6与拟南芥主要磷转运体PHT1;1和PHT1;4存在互作。电压钳实验发现，ROP6抑制PHT1;1和PHT1;4的磷转运活性。遗传学上下游分析表明，ROP6位于PHT1;1和PHT1;4的上游。该研究揭示了ROP6参与低磷胁迫的作用和分子机制，为农作物磷高效利用的遗传改良提供了新思路。

论文摘要：Phosphorus, an essential macroelement for plant growth and development,is a major limiting factor for sustainable crop yield. The Rho of plant (ROP) GTPase is involved in regulating multiple signal transduction processes in plants, but potentially including the phosphate deficiency signaling pathwayremains unknown. Here, we identified that the rop6 mutant exhibited a dramatic tolerant phenotype under Pi-deficient conditions, with higher phosphate accumulation and lower anthocyanin content. In contrast, the rop6 mutant was more sensitive to arsenate [As(V)] toxicity, the analog of Pi. Immunoblot analysis displayed that the ROP6 protein was rapidly degraded through ubiquitin/26S proteasome pathway under Pi-deficient conditions. In addition, pull-down assay using GST-RIC1 demonstrated that the ROP6 activity was decreased obviously under Pi-deficient conditions. Strikingly, protein-protein interaction and two‐voltage clamping assays demonstrated that ROP6 physically interacted with and inhibited the key phosphate uptake transporters PHT1;1 and PHT1;4 in vitro and in vivo. Moreover, genetic analysis showed that ROP6 functioned upstream of PHT1;1 and PHT1;4. Thus, we conclude that GTPase ROP6 modulates the uptake of phosphate by inhibiting the activities of PHT1;1 and PHT1;4 in Arabidopsis.

论文链接：https://www.jipb.net/EN/10.1111/jipb.13153